Liquid crystal display device

ABSTRACT

A liquid crystal display device includes a TFT substrate having a display region where pixels each having a TFT and a pixel electrode are formed in a matrix, a counter substrate having a display region where color filters of three colors are formed in a matrix, the TFT substrate and the counter substrate being bonded together with a sealing material in a seal portion at a periphery, and liquid crystal sealed between the TFT substrate and the counter substrate by the seal material. In the display region, a first insulation film, a first alignment film, a first columnar spacer, an overcoat film, a first color filter among the color filters of three colors are stacked in this order between the TFT substrate and the counter substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 12/832,193, filed Jul. 8, 2010, the contents of which areincorporated herein by reference.

CLAIM OF PRIORITY

The present application claims priority from Japanese application serialNo. 2009-161610 filed on Jul. 8, 2009, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device andmore particularly to a liquid crystal display device which does notcause air bubbles or liquid crystal leakage and thus is improved inreliability in a configuration of filling liquid crystal between a TFTsubstrate and a counter substrate by a one drop fill method.

2. Description of the Related Art

In liquid crystal display devices, liquid crystal is filled between aTFT substrate on which pixels each having a pixel electrode and a thinfilm transistor (TFT) are formed in a matrix and a counter substrate onwhich color filters and the like are formed, and an image is formed bycontrolling the molecules of the liquid crystal by an electric field.The gap between the TFT substrate and the counter substrate is asextremely small as several microns. In the conventional filling methodof liquid crystal, the space between the TFT substrate and the countersubstrate is sealed to create a vacuum within the space, and liquidcrystal is injected by means of atmospheric pressure.

However, when the gap between the TFT substrate and the countersubstrate is small, and the display area of the liquid crystal displaydevice is large, the injection requires a great deal of time, whichlengthens manufacturing throughput and thus increases the manufacturingcost. For addressing the problem, for example, a technique of sealingliquid crystal has been developed in which a required amount of liquidcrystal is dropped onto the counter substrate, and thereafter thecounter substrate and the TFT substrate are overlapped and sealed.

Such a one drop fill method has been conventionally employed forrelatively large liquid crystal display devices and has started to beused for small liquid crystal display devices. In small liquid crystaldisplay devices, a number of liquid crystal cells are formed on a mothersubstrate, and liquid crystal has to be sealed in each of the liquidcrystal cells. However, a number of man-hours are required for sealingliquid crystal into the individual liquid crystal cells. According tothe one drop fill method, liquid crystal can be injected into a numberof liquid crystal cells at one time in the mother substrate.

In the specification, while the “liquid crystal cell” refers to one in astate where the TFT substrate and the counter substrate are sealed witha sealing material, and liquid crystal is sealed therebetween, the“liquid crystal display device” refers to one on which a drive IC fordriving liquid crystal is mounted on the liquid crystal cell. However,they are sometimes used with no distinction.

In liquid crystal display devices, it is important to control the gapbetween the TFT substrate and the counter substrate. Conventionally, thegap is controlled by columnar spacers formed on the counter substrate ina display region and controlled by glass fibers in a seal portion.

On the other hand, JP-A-2001-174827 discloses a configuration of aliquid crystal display device in which columnar spacers are used in adisplay region, and columnar spacers are used also in a seal portion.JP-A-2001-174827 describes a configuration in which columnar spacers areformed on BM both in the display region and in the seal portion, so thatthe gap between the substrates in the display region is the same as thatof the seal portion.

On the other hand, the adhesion between the sealing material, and theTFT substrate and the counter substrate in the seal portion is importantfor reliability. JP-A-2007-212667 describes a configuration in which,for preventing the intrusion of liquid crystal between the sealingmaterial and the lower surface of the TFT substrate or the countersubstrate in the seal portion, a weir serving as a stopper againstliquid crystal is formed.

FIG. 14 is a plan view showing a state of a mother substrate 1000 formanufacturing small liquid crystal display devices. In FIG. 14, themother substrate 1000 is formed by overlapping a mother TFT substrateand a mother counter substrate. In the mother substrate 1000, 7×5=35pieces of liquid crystal cells 1 are fabricated. In FIG. 14, scribelines 2 for separating the mother substrate into the individual liquidcrystal cells 1 are marked, and a sealing material 20 is formed for eachof the liquid crystal cells 1. Liquid crystal is dropped in a regioninside the sealing material 20 and sealed with the sealing material 20.

In small liquid crystal display devices, a glass substrate is requiredto be thin. A glass substrate serving as a mother TFT substrate or amother counter substrate is standardized and is as thick as about 0.5mm. Therefore, after forming the mother substrate 1000, the mothersubstrate 1000 is reduced in thickness by polishing the outer surfacethereof. In this case, for preventing a polishing solution from enteringthe inside of the mother substrate 1000, a mother substrate sealingmaterial 2000 is formed at the peripheries of the mother TFT substrateand the mother counter substrate. Thereafter, the individual liquidcrystal cells 1 are separated from the mother substrate 1000 along thescribe lines 2.

In the liquid crystal one drop fill method, the amount of liquid crystalto be dropped is very important. When liquid crystal is dropped onto themother counter substrate, an accurately controlled amount of liquidcrystal is dropped in a region surrounded by the sealing material 20formed in the individual liquid crystal cell 1. Thereafter, the liquidcrystal is covered with the mother TFT substrate, and the mother TFTsubstrate and the mother counter substrate are bonded together with thesealing materials 20 and the mother substrate sealing material 2000. Inthis case, when the amount of liquid crystal to be dropped is too small,air bubbles are generated in the liquid crystal cell 1, and when theamount of liquid crystal to be dropped is too large, liquid crystalenters between the sealing material 20 and the TFT substrate or betweenthe sealing material 20 and the counter substrate, causing sealingdefects.

The capacity of the inside of the liquid crystal cell 1 is determined bythe height of a columnar spacer 205 formed in the display region. As theheight of the columnar spacer 205 is greater, the capacity of the insidebecomes large, and as the height of the columnar spacer 205 is smaller,the capacity of the inside becomes small. Accordingly, a proper droppingamount of liquid crystal varies depending on the height of the columnarspacer 205. However, the height of the columnar spacer 205 changesdepending on the process.

For addressing the problem, the height of the columnar spacer 205 formedon the counter substrate 200 is conventionally measured in each of thecounter substrates 200, the counter substrates 200 are divided intogroups according to the height of the columnar spacer 205, and thedropping amount of liquid crystal to be dropped onto the countersubstrate 200 is determined in each of the groups.

Although the gap between the TFT substrate 100 and the counter substrate200 is determined by the columnar spacers 205 in the display region, thegap between the TFT substrate 100 and the counter substrate 200 isconventionally determined by glass fibers 250 in the seal portion. FIG.15 is a schematic cross-sectional view showing this state. In FIG. 15, ablack matrix 202 and an overcoat film 203 are formed on the countersubstrate 200 side, and an inorganic passivation film 107 and an organicpassivation film 108 are formed on the TFT substrate 100 side. FIG. 15is a schematic view, and therefore the other layers are not illustrated.

In the display region indicated by DA in FIG. 15, the gap between thecounter substrate 200 and the TFT substrate 100 is determined by thecolumnar spacers 205 and determined in the seal portion by the diameterof the glass fiber 250 mixed in the sealing material. In FIG. 15, liquidcrystal 300 is sealed inside the sealing material.

Although a height HS of the columnar spacer 205 varies depending on theprocess, a diameter GH of the glass fiber 250 is controlled withrelatively high accuracy. When the counter substrates 200 are dividedinto groups according to the height of the columnar spacer 205, they aredivided into three groups: a group where the height HS of the columnarspacer 205 is substantially the same as the diameter GH of the glassfiber 250; a group where the height HS of the columnar spacer 205 issmaller than the diameter GH of the glass fiber 250; and a group wherethe height HS of the columnar spacer 205 is greater than the diameter HGof the glass fiber 250.

FIG. 16 is a cross-sectional view showing a state of the liquid crystalcell 1 of the group where the height HS of the columnar spacer 205 issubstantially the same as the diameter GH of the glass fiber 250. In theexample of FIG. 16, the amount of the liquid crystal 300 is properlycontrolled, and therefore the reliability of the seal portion can bemaintained at a high level. FIG. 17 is a cross-sectional view of theliquid crystal cell 1 in the group where the height HS of the columnarspacer 205 is smaller than the diameter GH of the glass fiber 250. Sincethe dropping amount of liquid crystal is determined by the height of thecolumnar spacer 205, an air bubble 400 is generated in this group like aregion A at the periphery shown in FIG. 17.

FIG. 18 is a cross-sectional view of the liquid crystal cell 1 in thegroup where the height HS of the columnar spacer 205 is greater than thediameter HG of the glass fiber 250. Since the dropping amount of theliquid crystal 300 is determined by the height of the columnar spacer205, tilting occurs in the seal portion and the substrate warps outwardin this group as indicated by a region B at the periphery shown in FIG.18. Although only the counter substrate 200 is warped in FIG. 18, FIG.18 is a schematic view, and actually the TFT substrate 100 side alsowarps.

FIG. 19 is a schematic view showing why tilting of the substrate occursin the seal portion. Dropping of liquid crystal is conducted underreduced pressure. Liquid crystal is dropped onto each of the liquidcrystal cells 1, the TFT substrate 100 and the counter substrate 200 areoverlapped each other, the sealing material is cured, and thereafter theTFT substrate 100 and the counter substrate 200 are returned to the air.Since a reduced pressure region 450 is formed between the liquid crystalcell 1 and the liquid crystal cell 1, that is, between the sealingmaterial and the sealing material, the substrate is deformed inward byatmospheric pressure indicated by open arrows. On the other hand, sincethe liquid crystal 300 is excessively dropped and sealed in a regioninside the sealing material, that is, on the liquid crystal cell 1 side,the substrate is deformed outward. Accordingly, tilting of the substrateoccurs in the seal portion.

When the mother substrate 1000 in this state is separated along thescribe line 2, the liquid crystal cell 1 has a cross-sectional shapeshown in FIG. 18. When the TFT substrate 100 or the counter substrate200 is reduced in thickness by polishing, the deformation of thesubstrate shown in FIG. 18 is likely to occur. As described above, whenthe liquid crystal 300 is excessively sealed, the reliability of theseal portion is impaired, and the contrast is reduced by a change in gapbetween the TFT substrate 100 and the counter substrate 200 at theperiphery of the display region.

SUMMARY OF THE INVENTION

In the conventional method as described above, even when the height ofthe columnar spacer 205 is measured to divide the counter substrates 200into groups according to the height of the columnar spacer 205, and theamount of liquid crystal to be dropped is controlled in each of thegroups, the air bubbles 400 due to too little liquid crystal and thedeformation of the substrate due to excessive liquid crystal are causedat a certain rate. It is an object of the invention to solve theabove-described problem and realize a liquid crystal display device withhigh reliability.

To achieve the object, the invention is specifically configured asfollows.

(1) A liquid crystal display device includes: a TFT substrate having adisplay region where pixels each having a TFT and a pixel electrode areformed in a matrix; a counter substrate having a display region wherecolor filters of three colors are formed in a matrix, the TFT substrateand the counter substrate being bonded together with a sealing materialin a seal portion at a periphery; and liquid crystal sealed between theTFT substrate and the counter substrate, wherein in the display region,a gap between the counter substrate and the TFT substrate is defined bya first columnar spacer formed on the counter substrate, and one colorfilter among the color filters of three colors is present below thefirst columnar spacer; and in the seal portion, a gap between thecounter substrate and the TFT substrate is defined by a second columnarspacer formed on the counter substrate, a first color filter among thecolor filters of three colors is formed in an island shape below thesecond columnar spacer, and a second color filter is stacked and formedin an island shape on the first color filter.

(2) The liquid crystal display device according to (1), wherein anovercoat film is present between the first columnar spacer and the colorfilter in the display region, and an overcoat film is present betweenthe second columnar spacer and the second color filter in the sealportion.

(3) The liquid crystal display device according to claim 1, wherein thefirst color filter is a green color filter, and the second color filteris a blue color filter.

(4) A liquid crystal display device includes: a TFT substrate having adisplay region where pixels each having a TFT and a pixel electrode areformed in a matrix; a counter substrate having a display region wherecolor filters of three colors are formed in a matrix, the TFT substrateand the counter substrate being bonded together with a sealing materialin a seal portion at a periphery; and liquid crystal sealed between theTFT substrate and the counter substrate, wherein in the display region,a gap between the counter substrate and the TFT substrate is defined bya first columnar spacer formed on the counter substrate, and one colorfilter among the color filters of three colors is present below thefirst columnar spacer; and in the seal portion, a gap between thecounter substrate and the TFT substrate is defined by a second columnarspacer formed on the counter substrate, a first color filter among thecolor filters of three colors is formed in an island shape below thesecond columnar spacer, a second color filter is stacked and formed inan island shape on the first color filter, and a third color filter isstacked and formed in an island shape on the second color filter.

(5) The liquid crystal display device according to (4), wherein anovercoat film is present between the first columnar spacer and the colorfilter in the display region, and an overcoat film is present betweenthe second columnar spacer and the third color filter in the sealportion.

(6) The liquid crystal display device according to (4), wherein thefirst color filter is a red color filter, the second color filter is agreen color filter, and the third color filter is a blue color filter.

(7) A liquid crystal display device includes: a TFT substrate having adisplay region where pixels each having a TFT and a pixel electrode areformed in a matrix; a counter substrate having a display region wherecolor filters of three colors are formed in a matrix, the TFT substrateand the counter substrate being bonded together with a sealing materialin a seal portion at a periphery; and liquid crystal sealed between theTFT substrate and the counter substrate, wherein in the display region,a gap between the counter substrate and the TFT substrate is defined bya first columnar spacer formed on the counter substrate, and one colorfilter among the color filters of three colors is present below thefirst columnar spacer; in the seal portion, a gap between the countersubstrate and the TFT substrate is defined by a second columnar spacerformed on the counter substrate, a first color filter among the colorfilters of three colors is formed in an island shape below the secondcolumnar spacer, and a second color filter is stacked and formed in anisland shape on the first color filter; and in the seal portion, a weirformed on the counter substrate is formed so as to surround the displayregion, and the color filters are not present below the weir.

According to an aspect of the invention, the difference between the gapbetween the TFT substrate and the counter substrate in the displayregion and the gap between the TFT substrate and the counter substratein the seal portion can be eliminated or can be always maintained at afixed value. Accordingly, in a liquid crystal display device of a typewhich injects liquid crystal by a one drop fill method, the reliabilityof the seal portion can be improved. Moreover, the generation of airbubbles in the display region can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a liquid crystal display device.

FIG. 2 is a cross-sectional view of a display region of the liquidcrystal display device.

FIG. 3 is a cross-sectional view of a seal portion of a liquid crystaldisplay device according to a first embodiment.

FIG. 4 is a cross-sectional view showing a structure in the vicinity ofa columnar spacer according to the first embodiment.

FIG. 5 is a plan view showing a display region of a counter substrate ofthe liquid crystal display device.

FIG. 6 is an exemplary plan view of a seal portion according to thefirst embodiment.

FIG. 7 is another exemplary plan view of a seal portion according to thefirst embodiment.

FIG. 8 is still another exemplary plan view of a seal portion accordingto the first embodiment.

FIG. 9 is a cross-sectional view of a seal portion of a liquid crystaldisplay device according to a second embodiment.

FIG. 10 is a cross-sectional view showing a structure in the vicinity ofa columnar spacer according to the second embodiment.

FIG. 11 is an exemplary plan view of a seal portion according to thesecond embodiment.

FIG. 12 is an exemplary plan view of a seal portion according to a thirdembodiment.

FIG. 13 is a cross-sectional view of the seal portion of a liquidcrystal display device according to the third embodiment.

FIG. 14 is a plan view of a mother substrate.

FIG. 15 shows an exemplary configuration for defining the gap betweensubstrates in a display region and in a seal portion in the related art.

FIG. 16 is a cross-sectional view of a liquid crystal display devicewhen the amount of liquid crystal is proper.

FIG. 17 is a cross-sectional view of the liquid crystal display devicewhen the amount of liquid crystal is too small.

FIG. 18 is a cross-sectional view of the liquid crystal display devicewhen the amount of liquid crystal is excessive.

FIG. 19 is a cross-sectional view of a mother substrate when the amountof liquid crystal is excessive.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the contents of the invention will be described in detailbased on embodiments.

First Embodiment

FIG. 1 is a plan view of a small liquid crystal display device used formobile phones or the like as an example of a product to which theinvention is applied. In FIG. 1, a counter substrate 200 is disposedabove a TFT substrate 100. A liquid crystal layer is interposed betweenthe TFT substrate and the counter substrate. The TFT substrate and thecounter substrate are bonded together with a sealing material 20 formedin a frame portion. In FIG. 1, since liquid crystal is sealed by a onedrop fill method, a filling port is not formed.

The TFT substrate 100 is formed larger than the counter substrate 200.In a portion of the TFT substrate 100 extended from the countersubstrate 200, a terminal portion 150 for supplying a power supply,video signals, scanning signals, and the like to a liquid crystal cell 1is formed.

In the terminal portion 150, an IC driver 50 for driving scanning lines,video signal lines, and the like is disposed. The IC driver 50 isdivided into three regions. At the center of the IC driver, a videosignal drive circuit 52 is disposed. A scanning signal drive circuit 51is disposed on both sides of the center.

In a display region 10 of FIG. 1, scanning lines 30 extend in thehorizontal direction and are arranged in the vertical direction.Moreover, video signal lines 40 extend in the vertical direction and arearranged in the horizontal direction. The scanning lines are connectedto the scanning signal drive circuit 51 of the IC driver 50 throughscanning-line lead lines 31. In FIG. 1, for arranging the display region10 at the center of the liquid crystal display device, the scanning-linelead lines 31 are arranged on both sides of the display region 10.Therefore, the scanning signal drive circuit 51 is disposed on bothsides in the IC driver 50. On the other hand, video-signal-line leadlines 41 which connect the video signal lines with the IC driver 50 arecollected on the lower side of a screen. The video-signal-line leadlines 41 are connected to the video signal drive circuit 52 arranged atthe central portion of the IC driver 50.

FIG. 2 is a cross-sectional view of the display region of the liquidcrystal display device shown in FIG. 1. FIG. 2 shows a cross-sectionalview of the display region of the liquid crystal display device of atypical TN type. However, the invention can be applied not only to TNtype liquid crystal display devices but also to another type liquidcrystal display devices such as of in-plane switching (IPS) type.

In FIG. 2, a gate electrode 101 is formed on the TFT substrate 100. Thegate electrode 101 is formed by sputtering and thereafter patterned byphotolithography. The gate electrode 101 is formed of Al and has athickness of about 300 nm.

The scanning lines, which are not shown, and the like are formedsimultaneously with and in the same layer as the gate electrode 101. Acommon wiring formed on the TFT substrate 100 for supplying a commonvoltage to a counter electrode 204 of the counter substrate 200 is alsoformed simultaneously in the same layer. A gate insulating film 102 isformed so as to cover the gate electrode 101. The gate insulating film102 is formed by, for example, sputtering a SiN film. The gateinsulating film 102 has a thickness of about 400 nm, for example.

A semiconductor layer 103 is formed above the gate electrode 101 via thegate insulating film 102. The semiconductor layer 103 is formed of a-Siand has a thickness of about 150 nm. A channel region of a TFT is formedin the a-Si layer. Before disposing a source electrode 105 and a drainelectrode 106 on the a-Si layer, an n+Si layer 104 is formed forestablishing ohmic contact between the a-Si layer and the sourceelectrode 105 or the drain electrode 106.

The source electrode 105 or the drain electrode 106 is formed on then+Si layer 104. In the same layer as the source electrode 105 or thedrain electrode 106, a ground wire and the like connected to the videosignal line, a protective diode, and the like are formed. The sourceelectrode 105 or the drain electrode 106 is formed of Mo, Al, or thelike. In the case of using Al, the upper and lower surfaces of an Allayer are covered with a Mo layer or the like. This is because when Alis in contact with ITO or the like in a contact hole 113 portion, acontact resistance sometimes becomes unstable.

After forming the source electrode 105 or the drain electrode 106,channel etching is conducted using the source electrode 105 and thedrain electrode 106 as masks. Etching is conducted to the upper portionof the a-Si layer for completely removing the n+Si layer 104 from thechannel layer, so that a channel-etching region 109 is formed.Thereafter, an inorganic passivation film 107 is formed so as to coverthe entire TFT. The inorganic passivation film 107 is formed of SiN. Theinorganic passivation film 107 has a thickness of about 400 nm, forexample.

An organic passivation film 108 is formed so as to cover the inorganicpassivation film 107. Since the organic passivation film 108 functionsas a planarization film, it is formed thick. The organic passivationfilm 108 is formed to a thickness of about from 2 μm to 3 μm. An acrylicresin is used for the organic passivation film 108, for example. Since aphotosensitive acrylic resin is used for the organic passivation film108, patterning can be conducted without using a resist.

Thereafter, the contact hole 113 is formed through the organicpassivation film 108 and the inorganic passivation film 107 forestablishing electrical continuity between a pixel electrode 110 formedof ITO and the source electrode 105 of the TFT. In the display region10, an ITO film serving as the pixel electrode 110 is formed on theorganic passivation film 108.

In FIG. 2, an alignment film 111 for aligning liquid crystal moleculesis formed on the pixel electrode 110. A liquid crystal layer 300 isinterposed between the TFT substrate 100 and the counter substrate 200.Initial alignment of liquid crystal molecules in the liquid crystallayer 300 is defined by the alignment film 111 formed on the TFTsubstrate 100 and an alignment film 111 formed on the counter substrate200.

In FIG. 2, a black matrix 202 as a light shielding film is formed on theinner side of the counter substrate 200 so as to correspond to theposition of the TFT. The black matrix functions as a light shieldingfilm for the TFT and functions to improve the contrast of an image. Acolor filter 201 is formed at a portion where the black matrix 202 isnot formed, that is, a portion forming a pixel.

In the pixel structure of FIG. 2, the color filters 201 of the samecolor are formed in a stripe in the vertical direction as will bedescribed later. The black matrixes are formed in a stripe in thehorizontal direction corresponding to the scanning lines 30 formed onthe TFT substrate 100. The color filters 201 are continuously formed ina stripe in the vertical direction so as to cover the black matrixes202.

An overcoat film 203 is formed so as to cover the color filter 201 andthe black matrix 202. The overcoat film 203 functions to moderateirregularities on the surface and functions to protect the color filteragainst liquid crystal. However, the overcoat film is not essential andmay not be used.

The counter electrode 204 is formed of an ITO film as a transparentconductive film on the overcoat film 203. Voltage is applied between thepixel electrode 110 formed in the pixel of the TFT substrate 100 and thecounter electrode 204 formed on the counter substrate 200 to rotateliquid crystal molecules, thereby controlling transmission light orreflection light to form an image.

A columnar spacer 205 for defining the gap between the counter substrate200 and the TFT substrate 100 is formed on the counter electrode 204.The columnar spacer 205 is formed at a portion where the black matrix202 is formed and through which light of a backlight or the like doesnot transmit. This is because the alignment of liquid crystal isdisturbed at the portion where the columnar spacer 205 is present tocause light leakage from the backlight or the like, thereby reducing thecontrast.

The columnar spacer 205 has a height of, for example, from 3 μm to 4 μm,which is the same as the thickness of the liquid crystal layer 300. Thecolumnar spacer 205 is formed of a photosensitive acrylic resin, forexample. When an acrylic resin is applied on the entire surface of thecounter substrate 200 and exposed to light through a mask, only aportion exposed to light is rendered insoluble in a developer, and onlythe exposed portion is left as the columnar spacer 205. Use of aphotosensitive resin eliminates a resist step, thereby shortening theprocess.

The alignment film 111 is formed so as to cover the columnar spacer 205and the counter electrode 204. Initial alignment of the liquid crystallayer 300 is determined by the alignment film 111 formed on the TFTsubstrate 100 and the alignment film 111 formed on the counter substrate200. This alignment state is changed by rotating liquid crystalmolecules with voltage applied between the pixel electrode 110 formed onthe TFT substrate 100 and the counter substrate 200, thereby controllinglight transmitting through the liquid crystal layer 300 to form animage.

FIG. 3 is a cross-sectional view of a region S formed with the sealingmaterial of the liquid crystal display device shown in FIG. 1, showing afeature of the invention. In FIG. 3, the scanning-line lead lines 31 areformed on the TFT substrate 100, and the gate insulating film 102 coversthe scanning-line lead lines 31. Scanning-line lead lines 31 formed in adifferent layer are formed on the gate insulating film 102. Although thescanning-line lead lines 31 extend in the vertical direction in theportion S in FIG. 1, the scanning-line lead lines 31 are formed in twolayers for reducing the area outside the display region (frame region)of the liquid crystal display device. The upper scanning-line lead lines31 are formed in the same layer as the video signal lines 40 andconnected to the scanning lines 30 at a not-shown portion via throughholes.

The inorganic passivation film 107 is formed so as to cover thescanning-line lead lines 31 in the second layer. The organic passivationfilm 108 is formed so as to cover the inorganic passivation film 107. Inthe seal portion, the pixel electrode 110 and the alignment film 111 arenot formed on the organic passivation film 108.

On the counter substrate 200 in FIG. 3, the black matrix 202 is formed.On the black matrix 202, a green color filter 201G and a blue colorfilter 201B are stacked and formed in an island shape. The green colorfilter 201G is formed larger than the blue color filter 201B. Theovercoat film 203 is formed so as to cover the green color filter 201Gand the blue color filter 201B. In the seal portion, the counterelectrode 204 and the alignment film 111 are not formed on the overcoatfilm 203.

In FIG. 3, the columnar spacer 205 is formed on the overcoat film 203.The sealing material 20 is filled around the columnar spacer 205. A tipend of the columnar spacer 205 is in contact with the organicpassivation film 108 formed on the TFT substrate 100. In the invention,the gap between the TFT substrate 100 and the counter substrate 200 isdefined by the columnar spacer 205 also in the seal portion.

The columnar spacer 205 in FIG. 3 is formed simultaneously with and bythe same process as the columnar spacer 205 in the display regiondescribed with reference to FIG. 2. Accordingly, even when a height HSof the columnar spacer 205 varies due to process variations, the heightvaries simultaneously in the display region and the seal portion.Therefore, the difference between the gap between the TFT substrate 100and the counter substrate 200 in the display region and the gap in theseal portion does not change depending on the process.

A feather of the invention is in that the island-shaped color filter 201having two layers is disposed below the columnar spacer 205. Asdescribed with reference to FIG. 2, the color filter 201 having onelayer is formed below the columnar spacer 205 in the display region. Inthe invention, for assuring the reliability of the seal portion, thecolor filter 201 is not formed on the entire surface of the seal portionbut is formed in an island shape. The overcoat film 203 is formed so asto cover the color filter 201 formed in an island shape.

Even when the color filter is manufactured under the same processconditions, the thickness thereof is smaller when it is formed in anisland shape like in the seal portion than when it is formed wide in astripe shape like in the display region. The overcoat film 203 on thecolor filter becomes thin when it is formed on the island-shaped colorfilter due to leveling effect. Accordingly, even when the height HS ofthe columnar spacer 205 is controlled so as to be the same in thedisplay region and in the seal portion, the thickness of the colorfilter formed in an island shape and the thickness of the overcoat film203 are reduced in the seal portion. Therefore, such a phenomenon occursin the seal portion that the gap between the TFT substrate 100 and thecounter substrate 200 is reduced.

In the invention, two layers of the island-shaped color filters 201G and201B are formed below the columnar spacer 205 in the seal portion,whereby the gap between the TFT substrate 100 and the counter substrate200 is controlled so as to be uniform in the display region and in theseal portion. As shown in FIG. 3, although the pixel electrode 110, thecounter electrode 204, the alignment film 111, and the like are notformed in the seal portion, the thicknesses of these films are small andtherefore fall within the error range compared to a change in thicknessof the color filter 201 or the overcoat film 203.

FIG. 4 is a cross-sectional view showing the shapes of the respectivefilms on the counter substrate 200 side in the seal portion. In FIG. 4,the black matrix 202 is formed in a solid manner on the countersubstrate 200. The island-shaped green color filter 201G having adiameter φ4 is formed on the black matrix 202. The φ4 is about from 60μm to 80 μm, for example. The island-shaped blue color filter 201Bhaving a diameter φ3 is formed on the island-shaped green color filter201G. The φ3 is about 40 μm, for example.

The overcoat film 203 is formed so as to cover the black matrix 202, theisland-shaped green color filter 201G, and the island-shaped blue colorfilter 201B. The columnar spacer 205 is formed on the overcoat film 203.The height HS of the columnar spacer 205 is, for example, from 3 μm to 4μm, which is the same as that of the display region. The columnar spacer205 has a diameter φ2 of about 15 μm at a root and a diameter φ1 ofabout 10 μm at a tip end.

FIG. 5 is a plan view showing a part of the display region of thecounter substrate 200. In FIG. 5, the black matrixes 202 are formed onthe counter substrate 200 so as to extend in the horizontal directionand are arranged in the vertical direction. Red color filters 201R, thegreen color filters 201G, and the blue color filters 201B cover theblack matrixes 202, extend in the vertical direction, and are arrangedin the horizontal direction at a specified pitch. A width X of each ofthe color filters 201 corresponds to the transverse diameter of asub-pixel, which is 40 μm, for example. A pitch Y of the black matrix202 corresponds to the vertical diameter of the sub-pixel, which is 120μm, for example.

In FIG. 5, the columnar spacers 205 are formed on the blue color filter201B so as to correspond to portions where the black matrixes 202 areformed. FIG. 5 shows an example in which the columnar spacer 205 isformed in all sub-pixels corresponding to blue pixels. In FIG. 5, forexample, the vertical pitch of the columnar spacer 205 is 120 μm, andthe horizontal pitch is also 120 μm. The forming density of the columnarspacers 205 may be smaller than that. The density of the columnarspacers 205 in the display region is determined depending on theconditions of use, for example, whether the liquid crystal displaydevice is used as a touch panel or not.

FIG. 6 is a plan view showing a seal portion of the counter substrate200 in the invention. In the seal portion, the columnar spacers 205 arearranged at a specified pitch, and the sealing material is formed aroundthe columnar spacers 205. Each of the columnar spacers 205 is formed onthe green color filter 201G and the blue color filter 201B both formedin an island shape. In FIG. 6, the overcoat film 203 is not illustrated.

A horizontal pitch d2 of the columnar spacer 205 is, for example, 200μm, and a vertical pitch d3 is, for example, 500 μm. A distance d1between the columnar spacer 205 and an edge of the sealing material is,for example, 100 μM. Accordingly, the color filter 201 serving as a baseof the columnar spacer 205 does not extend outside the sealing material.

FIG. 7 is a plan view showing another example of a seal portion of thecounter substrate 200 in the invention. In FIG. 7, a pitch d4 of thecolumnar spacer 205 in the vertical direction is reduced to half that ofFIG. 6. Accordingly, the density of the columnar spacers 205 is doubledin FIG. 7 compared to that of FIG. 6.

FIG. 8 is a plan view showing still another example of a seal portion ofthe counter substrate 200 in the invention. In FIG. 8, a pitch d5 of thecolumnar spacer 205 in the horizontal direction is reduced to half thepitch d2 in the horizontal direction in FIG. 6 or 7. A pitch d6 in thevertical direction in FIG. 8 is reduced to half the pitch in thevertical direction in FIG. 7. Accordingly, the density of the columnarspacers 205 is increased more in FIG. 8 than that of FIG. 7.

FIGS. 7 and 8 show examples of the arrangement and density of thecolumnar spacers 205 in the seal portion, and various arrangements, inaddition to the examples, can be adopted. Moreover, it is not necessarythat the density of the columnar spacers 205 in the seal portion be thesame as that of the display region. Depending on the intended use of theliquid crystal display device, the density of the columnar spacers 205can be determined such that the density is most suitable for each of thedisplay region and the seal portion.

Second Embodiment

FIG. 9 is a cross-sectional view of a seal portion according to a secondembodiment of the invention. The configuration of a display region inthe embodiment is the same as that of the first embodiment. In FIG. 9,the gap between the TFT substrate 100 and the counter substrate 200 inthe seal portion is determined by the columnar spacer 205 in the samemanner as the first embodiment.

In the embodiment, the red color filter 201R, the green color filter201G, and the blue color filter 201B are stacked and formed in an islandshape below the columnar spacer 205 in the seal portion. Since each ofthe color filters 201R, 201G, and 201B is formed in an island shape, thethickness thereof is likely to be smaller than that of the color filter201 formed in a stripe in the display region. Also the overcoat film 203formed on the color filter becomes thin when it is formed on theisland-shaped color filter due to the leveling effect.

As described above in the embodiment, the gap between the substrates isprevented from being different between the display region and the sealportion due to the reduced height of the base formed below the columnarspacer 205. In the configuration of the first embodiment, the greencolor filter 201G and the blue color filter 201B are formed below thecolumnar spacer 205, so that the gap between the substrates iscontrolled. In the embodiment, three layers of the color filters 201R,201G, and 201B are formed, so that the gap between the substrates iscontrolled.

On the other hand, it is advantageous for the reliability of the sealportion that the pressure within the liquid crystal cell be negativerather than positive. In this case, the gap between the substrates inthe seal portion is slightly greater than that of the display region. Insuch a case, use of the configuration of the embodiment allows stablesetting of the gap between the substrates.

FIG. 10 is a cross-sectional view showing the shapes of the respectivefilms on the counter substrate 200 side in the seal portion. Theconfiguration of FIG. 10 is the same as that of FIG. 4 except that theisland-shaped red color filter 201R is additionally disposed as the baseof the columnar spacer 205. Moreover, the diameter φ1 of the columnarspacer 205 at the tip end and the diameter φ2 at the root, the diameterφ3 of the island-shaped blue color filter 201B, and the diameter φ4 ofthe island-shaped green color filter 201G are the same as those of FIG.4. The diameter of the island-shaped red color filter 201R in FIG. 10 isfrom 100 μm to 120 μm, for example.

FIG. 11 is a plan view of a seal portion in the embodiment. In FIG. 11,the columnar spacers 205 are arranged at a predetermined pitch, and thesealing material is formed around the columnar spacers 205. Theconfiguration of FIG. 11 is the same as that of FIG. 4 of the firstembodiment except that the island-shaped red color filter 201R isformed, in addition to the island-shaped blue color filter 201B and theisland-shaped green color filter 201G, at the portion where the columnarspacer 205 is formed.

For the arrangement of the columnar spacers 205 in the embodiment, notonly the arrangement shown in FIG. 11 but also the arrangements of FIGS.7 and 8 described in the first embodiment and other arrangements can beadopted.

Third Embodiment

FIG. 12 is a plan view of a seal portion according to a third embodimentof the invention. The configuration of FIG. 12 is different from that ofthe first embodiment or the second embodiment in that a weir 500 forstopping the alignment film 111 is disposed substantially at the centralportion of the seal portion. The weir 500 is formed along the entiresealing material 20.

The presence of the alignment film 111 between the sealing material andthe substrate impairs the adhesive properties between the sealingmaterial and the substrate. The alignment film 111 is applied in thedisplay region in the form of liquid by an inkjet method or the like andthereafter solidified by baking. Upon applying the alignment film 111 inthe form of liquid, when the alignment film 111 flows into the sealportion, the reliability of the seal portion is reduced.

In the embodiment, for preventing the alignment film 111 in the form ofliquid from entering the entire seal portion even if the alignment filmflows into the seal portion, the weir 500 for stopping the alignmentfilm 111 is formed in the vicinity of the central portion of the sealportion. With this configuration, even if the alignment film 111 flowsinto the seal portion, the adhesion between the sealing material and thesubstrate can be sufficiently assured in the half region of the sealingmaterial. Therefore, the reliability of the seal portion can be assured.

In FIG. 12, the weir 500 can be formed of the same material and by thesame process as the columnar spacer 205. However, since the color filter201 is not disposed below the weir 500, a tip end of the weir 500 ispositioned lower than that of the columnar spacer 205 by the amount ofthe color filter. Accordingly, the gap between the TFT substrate 100 andthe counter substrate 200 in the seal portion is defined by the columnarspacer 205.

In FIG. 12, the columnar spacers 205 are arranged so as to avoid theweir 500. The pitch, arrangement, and the like of the columnar spacers205 in FIG. 12 is the same as those of FIG. 6 in the first embodiment.In addition, the various arrangements shown in the first embodiment canbe adopted for the arrangement of the columnar spacers 205 in the sealportion as long as they are arranged so as to avoid the weir 500.

FIG. 13 is a cross-sectional view of the seal portion of the liquidcrystal display device corresponding to a D-D cross-section in FIG. 12.That is, FIG. 13 shows the cross-section in which the weir 500 formed onthe counter substrate 200 is interposed between the columnar spacers. InFIG. 13, the columnar spacers 205 are arranged on the counter substrate200 side with the weir 500 interposed therebetween. The configuration ofeach of the columnar spacers 205 is the same as that described withreference to FIG. 3 of the first embodiment. In FIG. 13, the weir 500 isformed on the overcoat film 203. The weir 500 does not have a columnarshape but linearly extends in a direction perpendicular to the papersurface so as to surround the entire periphery of the display region.

The weir 500 is formed of the same material and by the same process asthe columnar spacer 205. Accordingly, the height HS of the columnarspacer 205 is the same as the height HS of the weir 500. However, sincethe base formed of the green color filter 201G and the blue color filter201B is not formed below the weir 500, the tip end of the weir 500 ispositioned lower than that of the columnar spacer 205. Accordingly, thegap between the TFT substrate 100 and the counter substrate 200 in theseal portion is determined by the columnar spacer 205.

In FIG. 13, the height HS of the weir 500 is equal to the height HS ofthe columnar spacer 205. For the effect of stopping the alignment film111, the height of the weir 500 may be lower than the height HS of thecolumnar spacer 205. For making the height of the weir 500 less thanthat of the columnar spacer 205, the width of the weir 500 is made lessthan the diameter of the columnar spacer 205. Even in the same process,the height can be made small when the width is small because of thenature of photolithography.

The display region is shown on the left of FIG. 13, where the alignmentfilm 111 is formed. FIG. 13 shows a state where the alignment film 111in the form of liquid flows into the seal portion when the alignmentfilm 111 is applied in the display region, and the alignment film 111 isstopped by the weir 500. Since the alignment film does not flow outsidethe weir 500, the alignment film 111 is not present between the sealingmaterial and the substrate outside the weir 500. Accordingly, highreliability can be assured in the seal portion at least outside the weir500.

The configuration of the columnar spacer 205 formed on the countersubstrate 200 in FIG. 13 is the same as that described in the firstembodiment. The other configurations of the counter substrate 200 arethe same as those described with reference to FIG. 1. The configurationof the TFT substrate 100 in FIG. 13 is the same as that described withreference to FIG. 3 of the first embodiment. The configuration of thedisplay region in the embodiment is the same as that described withreference to FIG. 2 of the first embodiment.

According to the invention as described above, since the weir 500 forpreventing the spreading of the alignment film into the seal portion isformed within the seal portion, even if the alignment film flows intothe seal portion, the minimum adhesive strength of the sealing materialcan be assured. Since the weir 500 can be formed by the same process asthat of the columnar spacer 205, the number of processes does notincrease due to the formation of the weir 500.

While there have been described what are at present considered to becertain embodiments of the invention, it will be understood that variousmodifications may be made thereto, and it is intended that the appendedclaims cover all such modifications as fall within the true spirit andscope of the invention.

What is claimed is:
 1. A display device comprising: a TFT substrateincluding a plurality of pixels each having a TFT and a pixel electrode;a counter substrate including a plurality of color filters; a pluralityof first protrusions formed outside of a display region, wherein, in thedisplay region, the plurality of color filters are formed on the countersubstrate; and a second protrusion formed outside of the display region,wherein the plurality of first protrusions are arranged in a firstdirection at intervals, the second protrusion extends in the firstdirection, a top of the first protrusions extend closer to the TFTsubstrate than a top of the second protrusion, the plurality of colorfilters are provided between the first protrusions and the countersubstrate, and the plurality of color filters are not provided betweenthe second protrusion and the counter substrate.
 2. The display deviceaccording to claim 1, wherein the second protrusion extends between theplurality of first protrusions.
 3. The display device according to claim1, wherein a width of the second protrusion is smaller than a width ofeach of the first protrusions.
 4. The display device according to claim1, wherein a stack of the plurality of color filters is provided betweenone of the first protrusions and the counter substrate.
 5. The displaydevice according to claim 1, wherein the TFT substrate and the countersubstrate are bonded together with a sealing material, liquid crystal issealed between the TFT substrate and the counter substrate, and asealing port of the liquid crystal is not formed on the sealingmaterial.
 6. The display device according to claim 1, wherein the TFTsubstrate and the counter substrate are bonded together with a sealingmaterial, liquid crystal is sealed between the TFT substrate and thecounter substrate, and an alignment film is formed between the countersubstrate and the liquid crystal.
 7. The display device according toclaim 1, further comprising a plurality of third protrusions formed inthe display region of the counter substrate, wherein the plurality ofcolor filters are provided between the third protrusions and the countersubstrate.
 8. The display device according to claim 7, wherein anarrangement density of the plurality of first protrusions is higher thanan arrangement density of the plurality of third protrusions.
 9. Thedisplay device according to claim 1, wherein a gap between the TFTsubstrate and the counter substrate outside the display region isgreater than a gap between the TFT substrate and the counter substratein the display region.
 10. The display device according to claim 1,wherein the plurality of color filters, which are provided between thefirst protrusions and the counter substrate, are different color filtersthat are stacked.
 11. The display device according to claim 1, whereinthe second protrusion is formed so as to surround the entire peripheryof the display region.